Use of alcohols containing at least two urethane groups for preparation of polyether polyols

ABSTRACT

The present invention relates to a process for preparing polyether polyols by adding alkylene oxides onto H-functional starter compounds, characterized in that at least one alcohol containing at least two urethane groups is used as H-functional starter compound. The invention further provides the polyether polyols containing a structural unit of the formula (IV) where R 1  is linear or branched C 2  to C 24 -alkylene which may optionally be interrupted by heteroatoms such as O, S or N and may be substituted, preferably CH 2 —CH 2  or CH 2 —CH(CH 3 ), R 2  is linear or branched C 2  to C 24 -alkylene, C 3  to C 24 -cycloalkylene, C 4  to C 24 -arylene, C 5  to C 24 -aralkylene, C 2  to C 24 -alkenylene, C 2  to C 24 -alkynylene, each of which may optionally by interrupted by heteroatoms such as O, S or N and/or may each be substituted by alkyl, aryl and/or hydroxyl, preferably C 2  to CM alkylene, R 3  is H, linear or branched C 1  to C 24 -alkyl, C 3  to C 24 -cycloalkyl, C 4  to C 24 -aryl, C 5  to C 24 -aralkyl, C 2  to C 24 -alkenyl, C 2  to C 24 -alkynyl, each of which may optionally be interrupted by heteroatoms such as O, S or N and/or each of which may be substituted by alkyl, aryl and/or hydroxyl, preferably H, R 4 , is H, linear or branched O to C 24 -alkyl, C 24 -cycloalkyl, C 4  to C 24 -aryl, C 5  to C 24 -aralkyl, C 2  to C 24 -alkenyl, C 2  to C 24 -alkynyl, each of which may be interrupted by heteroatoms such as O, S or N and/or each of which may be substituted by alkyl, aryl and/or hydroxyl, preferably H, IV is linear or branched C 2  to C 24 -alkylene which may optionally be interrupted by heteroatoms such as O, S or N and may be substituted, preferably CH 2 —CH 2  or CH 2 —CH(CH 3 ), and where R 1  to R 5  may be identical or different from one another, and the polyether polyols obtainable by the process according to the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a National Phase Application of PCT/EP2016/061216,filed May 19, 2016, which claims priority to European Application No.15169222.5, filed May 26, 2015, each of which are being incorporatedherein by reference.

FIELD

The present invention relates to a process for preparing polyetherpolyols by addition of alkylene oxides onto H-functional startercompounds, characterized in that at least one alcohol which contains atleast two urethane groups is used as H-functional starter compound. Theinvention further provides polyether polyols containing at least twourethane groups, the polyether polyols obtainable by the process of theinvention, the use of the polyether polyols of the invention forpreparation of a polyurethane polymer, and the resulting polyurethanepolymers.

BACKGROUND

The preparation of polyether carbonate polyols by catalytic reaction ofalkylene oxides (epoxides) and carbon dioxide in the presence ofH-functional starter substances (“starters”) has been the subject ofintensive study for more than 40 years (e.g. Inoue et al.,Copolymerization of Carbon Dioxide and Epoxide with OrganometallicCompounds; Die Makromolekulare Chemie 130, 210-220, 1969). This reactionis shown in schematic form in scheme (I), where R is an organic radicalsuch as alkyl, alkylaryl or aryl which may in each case also containheteroatoms, for example O, S, Si, etc., and where e, f, g and h areeach integers, and where the product shown here in scheme (I) for thepolyether carbonate polyol should be understood as meaning merely thatblocks having the structure shown may in principle be retained in thepolyether carbonate polyol obtained but the sequence, number and lengthof the blocks and the OH functionality of the starter may vary and isnot restricted to the polyether carbonate polyol shown in scheme (I).This reaction (see scheme (I)) is highly advantageous from anenvironmental standpoint since this reaction comprises converting agreenhouse gas such as CO₂ into a polymer. A further product formed,actually a by-product, is the cyclic carbonate shown in scheme (I) (forexample propylene carbonate when R═CH₃, also referred to hereinafter ascPC, or ethylene carbonate when R═H, also referred to hereinafter ascEC).

U.S. Pat. No. 3,829,505 and DE 1 595 759 describe the possibility ofreacting OH-functional starter compounds in excess with aromaticpolyisocyanates, in order to arrive in this way at polyurethane polyolscontaining OH groups and having at least 2 urethane groups, which can beused as starter oligomers for the DMC catalysis.

U.S. Pat. No. 3,654,224 describes the possibility of using amides,especially aromatic amides, for example benzamide, as starter compoundfor the DMC catalysis.

SUMMARY

It was therefore an object of the present invention to utilize thecyclic carbonate obtained as a by-product for the preparation ofpolyether polyols. Preferably, the polyether polyols thus obtainable areto be suitable for the preparation of polyurethanes, especially offlexible polyurethane foams.

This object is achieved in accordance with the invention by a processfor preparing polyether polyols by addition of alkylene oxides ontoH-functional starter compounds, characterized in that at least onealcohol containing at least two urethane groups is used as H-functionalstarter compound.

Preferably, the process of the invention for preparing polyether polyolsby addition of alkylene oxides onto H-functional starter compounds ischaracterized in that at least one alcohol containing two urethanegroups is used as H-functional starter compound.

DETAILED DESCRIPTION

Particular preference is given to the process of the invention forpreparing polyether polyols by addition of alkylene oxides ontoH-functional starter compounds, characterized in that at least onealcohol of formula (II) is used as H-functional starter compound

where

-   R¹ is linear or branched C₂- to C₂₄-alkylene which may optionally be    interrupted by heteroatoms such as O, S or N and may be substituted,    preferably CH₂—CH₂ or CH₂—CH(CH₃),-   R² is linear or branched C₂ to C₂₄-alkylene, C₃ to    C₂₄-cycloalkylene, C₄ to C₂₄-arylene, C₅ to C₂₄-aralkylene, C₂ to    C₂₄-alkenylene, C₂ to C₂₄-alkynylene, each of which may optionally    be interrupted by heteroatoms such as O, S or N and/or each of which    may be substituted by alkyl, aryl and/or hydroxyl, preferably C₂ to    C₂₄-alkylene,-   R³ is H, linear or branched C₁ to C₂₄-alkyl, C₃ to C₂₄-cycloalkyl,    C₄ to C₂₄-aryl, C₅ to C₂₄-aralkyl, C₂ to C₂₄-alkenyl, C₂ to    C₂₄-alkynyl, each of which may optionally be interrupted by    heteroatoms such as O, S or N and/or each of which may be    substituted by alkyl, aryl and/or hydroxyl, preferably H,-   R⁴ is H, linear or branched C₁ to C₂₄-alkyl, C₃ to C₂₄-cycloalkyl,    C₄ to C₂₄-aryl, C₅ to C₂₄-aralkyl, C₂ to C₂₄-alkenyl, C₂ to    C₂₄-alkynyl, each of which may optionally be interrupted by    heteroatoms such as O, S or N and/or each of which may be    substituted by alkyl, aryl and/or hydroxyl, preferably H,-   R⁵ is linear or branched C₂ to C₂₄-alkylene which may optionally be    interrupted by heteroatoms such as O, S or N and may be substituted,    preferably CH₂—CH₂ or CH₂—CH(CH₃),    and where R¹ to R⁵ may be identical or different.

The use of the word a in connection with countable parameters should beunderstood here and hereinafter to mean the number one only when this isevident from the context (for example through the wording “exactlyone”). Otherwise, expressions such as “an alkylene oxide”, “an alcoholcontaining at least two urethane groups” etc. always refer to thoseembodiments in which two or more alkylene oxides, two or more alcoholscontaining at least two urethane groups, etc. are used.

The invention is illustrated in detail hereinafter. Various embodimentscan be combined here with one another as desired, unless the opposite isapparent to the person skilled in the art from the context.

The alcohols containing at least two urethane groups are obtainable byreacting cyclic carbonates with compounds containing at least two aminogroups. Preferably, the alcohols containing two urethane groups areobtainable by reacting propylene carbonate and/or ethylene carbonatewith compounds containing two amino groups.

The particularly preferred alcohols of the formula (II) are obtainableby reacting cyclic carbonates with diamines of formula (III)

HN(R³)—R²—NH(R⁴)  (III)

where R², R³ and R⁴ are as defined above, where R³ and R⁴ may beidentical or different.

Cyclic carbonates used are preferably propylene carbonate and/orethylene carbonate.

Most preferably, the alcohols of the formula (II) are obtainable byreacting propylene carbonate and/or ethylene carbonate with diamines offormula (III).

More preferably, the alcohols of the formula (II) are obtainable byreacting propylene carbonate and/or ethylene carbonate with at least onecompound selected from the group consisting of 1,2-ethanediamine,diaminopropane, diaminopentane, diaminohexane, diaminooctane,diaminodecane, diaminododecane, diaminooctadecane, diaminoeicosane,isophoronediamine, tolylenediamine, and methylenedianiline.

The reaction of the cyclic carbonates with the compounds containing atleast two amino groups is effected preferably at 40 to 80° C., morepreferably at 55 to 65° C. The reaction time is preferably 5 to 40 h,more preferably 10 to 30 h.

In a particularly advantageous embodiment, the cyclic carbonate is usedin excess. Preferably, the molar ratio of cyclic carbonate to the aminogroups of the compounds containing at least two amino groups is 1.05 to3, more preferably from 1.1 to 2, most preferably from 1.2 to 1.6. Theexcess cyclic carbonate can either be removed directly after thesynthesis of the alcohol containing at least two urethane groups bythin-film evaporation, for example, or can remain in the alcoholcontaining at least two urethane groups and be used in the polyetherpolyol preparation as well. In the second case mentioned, the excesscyclic carbonate is removed from the product after the polyether polyolpreparation.

As well as the alcohols containing at least two urethane groups, it isadditionally also possible to use H-functional starter compounds lackingurethane groups in the process of the invention, these being describedhereinafter. Suitable H-functional starter substances (“starters”)employed may be compounds having alkoxylation-active hydrogen atoms andhaving a molar mass of 18 to 4500 g/mol, preferably of 62 to 500 g/moland more preferably of 62 to 182 g/mol. The ability to use a starterhaving a low molar mass is a distinct advantage over the use ofoligomeric starters prepared by means of a prior alkoxylation. Inparticular, a level of economic viability is achieved that is madepossible by the omission of a separate alkoxylation process.

Groups active in respect of the alkoxylation and having active hydrogenatoms are, for example, —OH, —NH₂ (primary amines), —NH— (secondaryamines), —SH, and —CO₂H, preferably —OH and —NH₂, more preferably —OH.H-Functional starter substances used are, for example, one or morecompounds selected from the group consisting of mono- and polyhydricalcohols, polyfunctional amines, polyfunctional thiols, amino alcohols,thio alcohols, hydroxy esters, polyether polyols, polyester polyols,polyester ether polyols, polyether carbonate polyols, polycarbonatepolyols, polycarbonates, polyethyleneimines, polyetheramines,polytetrahydrofurans (e.g. PolyTHF® from BASF), polytetrahydrofuranamines, polyether thiols, polyacrylate polyols, castor oil, the mono- ordiglyceride of castor oil, monoglycerides of fatty acids, chemicallymodified mono-, di- and/or triglycerides of fatty acids, and C₁-C₂₄alkyl fatty acid esters containing an average of at least 2 OH groupsper molecule. By way of example, the C₁-C₂₄-alkyl fatty acid esterscontaining an average of at least 2 OH groups per molecule arecommercial products such as Lupranol Balance® (from BASF AG), Merginol®products (from Hobum Oleochemicals GmbH), Sovermol® products (fromCognis Deutschland GmbH & Co. KG) and Soyol® TM products (from USSCCo.).

Monofunctional starter substances used may be alcohols, amines, thiolsand carboxylic acids. Monofunctional alcohols used may be: methanol,ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol,3-buten-1-ol, 3-butyn-1-ol, 2-methyl-3-buten-2-ol,2-methyl-3-butyn-2-ol, propargyl alcohol, 2-methyl-2-propanol,1-tert-butoxy-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol,2-hexanol, 3-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol,2-octanol, 3-octanol, 4-octanol, phenol, 2-hydroxybiphenyl,3-hydroxybiphenyl, 4-hydroxybiphenyl, 2-hydroxypyridine,3-hydroxypyridine, 4-hydroxypyridine. Useful monofunctional aminesinclude: butylamine, tert-butylamine, pentylamine, hexylamine, aniline,aziridine, pyrrolidine, piperidine, morpholine. Monofunctional thiolsused may be: ethanethiol, 1-propanethiol, 2-propanethiol, 1-butanethiol,3-methyl-1-butanethiol, 2-butene-1-thiol, thiophenol. Monofunctionalcarboxylic acids include: formic acid, acetic acid, propionic acid,butyric acid, fatty acids such as stearic acid, palmitic acid, oleicacid, linoleic acid, linolenic acid, benzoic acid, acrylic acid.

Polyhydric alcohols suitable as H-functional starter substances are, forexample, dihydric alcohols (for example ethylene glycol, diethyleneglycol, propylene glycol, dipropylene glycol, 1,3-propanediol,1,4-butanediol, 1,4-butenediol, 1,4-butynediol, neopentyl glycol,1,5-pentanediol, methylpentanediols (for example3-methyl-1,5-pentanediol), 1,6-hexanediol, 1,8-octanediol,1,10-decanediol, 1,12-dodecanediol, bis(hydroxymethyl)cyclohexanes (forexample 1,4-bis(hydroxymethyl)cyclohexane), triethylene glycol,tetraethylene glycol, polyethylene glycols, dipropylene glycol,tripropylene glycol, polypropylene glycols, dibutylene glycol andpolybutylene glycols); trihydric alcohols (for exampletrimethylolpropane, glycerol, trishydroxyethyl isocyanurate, castoroil); tetrahydric alcohols (for example pentaerythritol); polyalcohols(for example sorbitol, hexitol, sucrose, starch, starch hydrolyzates,cellulose, cellulose hydrolyzates, hydroxy-functionalized fats and oils,especially castor oil), and all the modification products of theseaforementioned alcohols with different amounts of ε-caprolactone.

The H-functional starter substances may also be selected from thesubstance class of the polyether polyols having a molecular weight M_(n)in the range from 18 to 4500 g/mol and a functionality of 2 to 3.Preference is given to polyether polyols formed from repeat ethyleneoxide and propylene oxide units, preferably having a proportion ofpropylene oxide units of 35% to 100%, particularly preferably having aproportion of propylene oxide units of 50% to 100%. These may be randomcopolymers, gradient copolymers, alternating copolymers or blockcopolymers of ethylene oxide and propylene oxide. More particularly,polyether polyols obtainable by the process according to the inventiondescribed here are used. For this purpose, these polyether polyols usedas H-functional starter substances are prepared in a separate reactionstep beforehand.

The H-functional starter substances may also be selected from thesubstance class of the polyester polyols. The polyester polyols used areat least difunctional polyesters. Preferably, polyester polyols consistof alternating acid and alcohol units. Acid components used are, forexample, succinic acid, maleic acid, maleic anhydride, adipic acid,phthalic anhydride, phthalic acid, isophthalic acid, terephthalic acid,tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalicanhydride or mixtures of the acids and/or anhydrides mentioned. Alcoholcomponents used are, for example, ethanediol, propane-1,2-diol,propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, neopentyl glycol,hexane-1,6-diol, 1,4-bis(hydroxymethyl)cyclohexane, diethylene glycol,dipropylene glycol, trimethylolpropane, glycerol, pentaerythritol ormixtures of the alcohols mentioned. Employing dihydric or polyhydricpolyether polyols as the alcohol component affords polyester etherpolyols which can likewise serve as starter substances for preparationof the polyether carbonate polyols.

In addition, H-functional starter substances used may be polycarbonatediols which are prepared, for example, by reaction of phosgene, dimethylcarbonate, diethyl carbonate or diphenyl carbonate and difunctionalalcohols or polyester polyols or polyether polyols. Examples ofpolycarbonates may be found, for example, in EP-A 1359177.

In a further embodiment of the invention, it is possible to usepolyether carbonate polyols as H-functional starter substances.

The H-functional starter substances generally have a functionality (i.e.the number of hydrogen atoms active in respect of the polymerization permolecule) of 1 to 8, preferably of 2 or 3. The H-functional startersubstances are used either individually or as a mixture of at least twoH-functional starter substances.

More preferably, the H-functional starter substances are one or morecompounds selected from the group consisting of ethylene glycol,propylene glycol, propane-1,3-diol, butane-1,3-diol, butane-1,4-diol,pentane-1,5-diol, 2-methylpropane-1,3-diol, neopentyl glycol,hexane-1,6-diol, octane-1,8-diol, diethylene glycol, dipropylene glycol,glycerol, trimethylolpropane, pentaerythritol, sorbitol and polyetherpolyols having a molecular weight Mn in the range from 150 to 4500 g/moland a functionality of 2 to 3.

The invention further provides polyether polyols containing a structuralunit of the formula (IV)

where R¹, R², R³, R⁴ and R⁵ are as defined above. Preferably, thepolyether polyols of the invention contain exactly one single structuralunit of the formula (IV) per polyether polyol molecule.

The polyether polyols of the invention preferably have an OH number of 3to 400 mg KOH/g, more preferably 10 to 200 mg KOH/g.

In addition, the polyether polyols of the invention have a functionalityof 2.0 to 4.0, preferably of 2.05 to 3.0.

The present invention further provides a process for preparing polyetherpolyols by adding alkylene oxides onto H-functional starter compounds,characterized in that at least one alcohol containing at least twourethane groups, preferably an alcohol of formula (II), is used asH-functional starter compound and the addition is effected in thepresence of at least one double metal cyanide catalyst (also referred toas DMC catalyst).

DMC catalysts suitable for the process of the invention are known inprinciple from the prior art (see, for example, U.S. Pat. No. 3,404,109,U.S. Pat. No. 3,829,505, U.S. Pat. No. 3,941,849 and U.S. Pat. No.5,158,922). DMC catalysts which are described, for example, in U.S. Pat.No. 5,470,813, EP-A-0 700 949, EP-A-0 743 093, EP-A-0 761 708, WO97/40086, WO 98/16310 and WO 00/47649 have a very high activity in thepolymerization of alkylene oxides and, in some cases, thecopolymerization of alkylene oxides with suitable comonomers, forexample lactones, cyclic carboxylic anhydrides, lactides, cycliccarbonates or carbon dioxide, and enable the preparation of polymericpolyols at very low catalyst concentrations (25 ppm or less), such thatthere is generally no longer any need to separate the catalyst from thefinished product. A typical example is that of the highly active DMCcatalysts which are described in EP-A-0 700 949 and contain not only adouble metal cyanide compound (e.g. zinc hexacyanocobaltate(III)) and anorganic complex ligand (e.g. tert-butanol) but also a polyether having anumber-average molecular weight greater than 500 g/mol. It is alsopossible to use the alkaline DMC catalysts disclosed in WO 2011/144523.

Cyanide-free metal salts suitable for preparation of the double metalcyanide compounds preferably have the general formula (V)

M(X)_(n)  (V)

where

M is selected from the metal cations Zn²⁺, Fe²⁺, Ni²⁺, Mn²⁺, Co²⁺, Sr²⁺,Sn²⁺, Pb²⁺ and Cu²⁺; M is preferably Zn²⁺, Fe²⁺, Co²⁺ or Ni²⁺,

X is one or more (i.e. different) anions, preferably an anion selectedfrom the group of the halides (i.e. fluoride, chloride, bromide,iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate,isocyanate, isothiocyanate, carboxylate, oxalate and nitrate;

n is 1 when X=sulfate, carbonate or oxalate and

n is 2 when X=halide, hydroxide, cyanate, thiocyanate, isocyanate,isothiocyanate or nitrate;

or suitable cyanide-free metal salts have the general formula (VI)

M_(r)(X)₃  (VI)

where

M is selected from the metal cations Fe³⁺, Al³⁺ and Cr³⁺,

X is one or more (i.e. different) anions, preferably an anion selectedfrom the group of the halides (i.e. fluoride, chloride, bromide,iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate,isocyanate, isothiocyanate, carboxylate, oxalate and nitrate;

r is 2 when X=sulfate, carbonate or oxalates and

r is 1 when X=halide, hydroxide, cyanate, thiocyanate, isocyanate,isothiocyanate, carboxylate or nitrate,

or suitable cyanide-free metal salts have the general formula (VII)

M(X)_(s)  (VII)

where

M is selected from the metal cations Mo⁴⁺, V⁴⁺ and W⁴⁺,

X is or more (i.e. different) anions, preferably an anion selected fromthe group of the halides (i.e. fluoride, chloride, bromide, iodide),hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate,isothiocyanate, carboxylate, oxalate and nitrate;

s is 2 when X=sulfate, carbonate or oxalate and

s is 4 when X=halide, hydroxide, cyanate, thiocyanate, isocyanate,isothiocyanate, carboxylate or nitrate,

or suitable cyanide-free metal salts have the general formula (VIII)

M(X)_(t)  (VIII)

where

M is selected from the metal cations Mo⁶⁺ and W⁶⁺,

X is one or more (i.e. different) anions, preferably an anion selectedfrom the group of the halides (i.e. fluoride, chloride, bromide,iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate,isocyanate, isothiocyanate, carboxylate, oxalate and nitrate;

t is 3 when X=sulfate, carbonate or oxalate and

t is 6 when X=halide, hydroxide, cyanate, thiocyanate, isocyanate,isothiocyanate, carboxylate or nitrate.

Examples of suitable cyanide-free metal salts are zinc chloride, zincbromide, zinc iodide, zinc acetate, zinc acetylacetonate, zinc benzoate,zinc nitrate, iron(II) sulfate, iron(II) bromide, iron(II) chloride,cobalt(II) chloride, cobalt(II) thiocyanate, nickel(II) chloride andnickel(II) nitrate. It is also possible to use mixtures of differentmetal salts.

Metal cyanide salts suitable for preparation of the double metal cyanidecompounds preferably have the general formula (IX)

(Y)_(a)M′(CN)_(b)(A)_(c)  (IX)

where

M′ is selected from one or more metal cations from the group consistingof Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III),Ir(III), Ni(II), Rh(III), Ru(II), V(IV) and V(V); M′ is preferably oneor more metal cations from the group consisting of Co(II), Co(III),Fe(II), Fe(III), Cr(III), Ir(III) and Ni(II),

Y is selected from one or more metal cations from the group consistingof alkali metal (i.e. Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺) and alkaline earth metal(i.e. Be²⁺, Ca²⁺, Mg²⁺, Sr²⁺, Ba²⁺)

A is selected from one or more anions of the group consisting of halides(i.e. fluoride, chloride, bromide, iodide), hydroxide, sulfate,carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate,carboxylate, oxalate or nitrate and

a, b and c are integers, the values for a, b and c being selected suchas to ensure the electronic neutrality of the metal cyanide salt; a ispreferably 1, 2, 3 or 4; b is preferably 4, 5 or 6; c preferably has thevalue 0.

Examples of suitable metal cyanide salts are potassiumhexacyanocobaltate(III), potassium hexacyanoferrate(II), potassiumhexacyanoferrate(III), calcium hexacyanocobaltate(III) and lithiumhexacyanocobaltate(III).

Preferred double metal cyanide compounds present in the DMC catalystsare compounds of general formula (X)

Mx[M′x,(CN)y]z  (X)

in which M is defined as in formula (V) to (VIII) and

M′ is as defined in formula (IX), and

x, x′, y and z are integers and are chosen so as to ensure electronicneutrality of the double metal cyanide compound.

Preferably,

x=3, x′=1, y=6 and z=2,

M=Zn(II), Fe(II), Co(II) or Ni(II) and

M′=Co(III), Fe(III), Cr(III) or Ir(III).

Examples of suitable double metal cyanide compounds are zinchexacyanocobaltate(III), zinc hexacyanoiridate(III), zinchexacyanoferrate(III) and cobalt(II) hexacyanocobaltate(III). Furtherexamples of suitable double metal cyanide compounds can be found, forexample, in U.S. Pat. No. 5,158,922 (column 8, lines 29-66). Particularpreference is given to using zinc hexacyanocobaltate(III).

The organic complex ligands added in the preparation of the DMCcatalysts are disclosed, for example, in U.S. Pat. No. 5,158,922 (seeespecially column 6 lines 9 to 65), U.S. Pat. No. 3,404,109, U.S. Pat.No. 3,829,505, U.S. Pat. No. 3,941,849, EP-A-0 700 949, EP-A-0 761 708,JP-A-4145123, U.S. Pat. No. 5,470,813, EP-A-0 743 093 and WO-A-97/40086.The organic complex ligands used are, for example, water-soluble organiccompounds containing heteroatoms such as oxygen, nitrogen, phosphorus orsulfur, which can form complexes with the double metal cyanide compound.Preferred organic complex ligands are alcohols, aldehydes, ketones,ethers, esters, amides, ureas, nitriles, sulfides and mixtures thereof.Particularly preferred organic complex ligands are aliphatic ethers(such as dimethoxyethane), water-soluble aliphatic alcohols (such asethanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol,2-methyl-3-buten-2-ol and 2-methyl-3-butyn-2-ol), compounds whichcontain both aliphatic or cycloaliphatic ether groups and aliphatichydroxyl groups (for example ethylene glycol mono-tert-butyl ether,diethylene glycol mono-tert-butyl ether, tripropylene glycol monomethylether and 3-methyl-3-oxetanemethanol). Extremely preferred organiccomplex ligands are selected from one or more compounds of the groupconsisting of dimethoxyethane, tert-butanol 2-methyl-3-buten-2-ol,2-methyl-3-butyn-2-ol, ethylene glycol mono-tert-butyl ether and3-methyl-3-oxetanemethanol.

Optionally used in the preparation of the DMC catalysts are one or morecomplex-forming component(s) from the compound classes of thepolyethers, polyesters, polycarbonates, polyalkylene glycol sorbitanesters, polyalkylene glycol glycidyl ethers, polyacrylamide,poly(acrylamide-co-acrylic acid), polyacrylic acid, poly(acrylicacid-co-maleic acid), polyacrylonitrile, polyalkyl acrylates, polyalkylmethacrylates, polyvinyl methyl ethers, polyvinyl ethyl ethers,polyvinyl acetate, polyvinyl alcohol, poly-N-vinylpyrrolidone,poly(N-vinylpyrrolidone-co-acrylic acid), polyvinyl methyl ketone,poly(4-vinylphenol), poly(acrylic acid-co-styrene), oxazoline polymers,polyalkyleneimines, maleic acid and maleic anhydride copolymers,hydroxyethyl cellulose and polyacetals, or of the glycidyl ethers,glycosides, carboxylic esters of polyhydric alcohols, gallic acids orsalts, esters or amides thereof, cyclodextrins, phosphorus compounds,α,β-unsaturated carboxylic esters or ionic surface- or interface-activecompounds.

Preferably, in the preparation of the DMC catalysts, in the first step,the aqueous solutions of the metal salt (e.g. zinc chloride), used in astoichiometric excess (at least 50 mol %) based on metal cyanide salt(i.e. at least a molar ratio of cyanide-free metal salt to metal cyanidesalt of 2.25:1.00), and the metal cyanide salt (e.g. potassiumhexacyanocobaltate) are converted in the presence of the organic complexligand (e.g. tert-butanol), such that a suspension is formed comprisingthe double metal cyanide compound (e.g. zinc hexacyanocobaltate), water,excess cyanide-free metal salt, and the organic complex ligands. Thisorganic complex ligand may be present in the aqueous solution of thecyanide-free metal salt and/or of the metal cyanide salt, or it is addeddirectly to the suspension obtained after precipitation of the doublemetal cyanide compound. It has been found to be advantageous to mix theaqueous solutions of the cyanide-free metal salt and of the metalcyanide salt and the organic complex ligands by stirring vigorously.Optionally, the suspension formed in the first step is subsequentlytreated with a further complex-forming component. The complex-formingcomponent is preferably used in a mixture with water and organic complexligand. A preferred process for performing the first step (i.e. thepreparation of the suspension) comprises using a mixing nozzle,particularly preferably using a jet disperser, as described inWO-A-01/39883.

In the second step, the solid (i.e. the precursor of the inventivecatalyst) is isolated from the suspension by known techniques, such ascentrifugation or filtration.

In a preferred execution variant for preparing the catalyst, theisolated solid is subsequently washed in a third process step with anaqueous solution of the organic complex ligand (for example byresuspension and subsequent reisolation by filtration orcentrifugation). In this way, it is possible to remove, for example,water-soluble by-products such as potassium chloride from the catalyst.Preferably, the amount of the organic complex ligand in the aqueous washsolution is between 40% and 80% by weight, based on the overallsolution.

Further complex-forming component is optionally added to the aqueouswash solution in the third step, preferably in the range between 0.5%and 5% by weight, based on the overall solution.

It is moreover advantageous to wash the isolated solid more than once.For this purpose, for example, the first washing procedure can berepeated. It is preferable, however, to use non-aqueous solutions forfurther washing operations, e.g. a mixture of organic complex ligandsand other complex-forming components.

The isolated and optionally washed solid is subsequently, optionallyafter pulverization, dried at temperatures of generally 20-100° C. andat pressures of generally 0.1 mbar to standard pressure (1013 mbar).

A preferred process for isolating the DMC catalysts from the suspensionby filtration, filtercake washing and drying is described inWO-A-01/80994.

The concentration of DMC catalyst used is 5.0 ppm to 1000 ppm,preferably 10 ppm to 900 ppm and more preferably 20 ppm to 80 ppm, basedon the mass of the polyether polyol to be prepared. According to theprofile of requirements for the downstream use, the DMC catalyst can beleft in the product or (partly) removed. The (partial) removal of theDMC catalyst can be effected, for example, by treatment with adsorbents.Methods of removing DMC catalysts are described, for example, in U.S.Pat. No. 4,987,271, DE-A-3132258, EP-A-0 406 440, U.S. Pat. No.5,391,722, U.S. Pat. No. 5,099,075, U.S. Pat. No. 4,721,818, U.S. Pat.No. 4,877,906 and EP-A-0 385 619.

Alkylene oxides suitable for the process of the invention have 2 to 24carbon atoms. The alkylene oxides having 2 to 24 carbon atoms arepreferably one or more compounds selected from the group consisting ofethylene oxide, propylene oxide, 1-butene oxide, 2,3-butene oxide,2-methyl-1,2-propene oxide (isobutene oxide), 1-pentene oxide,2,3-pentene oxide, 2-methyl-1,2-butene oxide, 3-methyl-1,2-butene oxide,1-hexene oxide, 2,3-hexene oxide, 3,4-hexene oxide, 2-methyl-1,2-penteneoxide, 4-methyl-1,2-pentene oxide, 2-ethyl-1,2-butene oxide, 1-hepteneoxide, 1-octene oxide, 1-nonene oxide, 1-decene oxide, 1-undecene oxide,1-dodecene oxide, 4-methyl-1,2-pentene oxide, butadiene monoxide,isoprene monoxide, cyclopentene oxide, cyclohexene oxide, cyclohepteneoxide, cyclooctene oxide, styrene oxide, methylstyrene oxide, pineneoxide, mono- or polyalkylene oxidized fats as mono-, di- andtriglycerides, alkylene oxidized fatty acids, C₁-C₂₄ esters of alkyleneoxidized fatty acids, epichlorohydrin, glycidol, and derivatives ofglycidol, for example methyl glycidyl ether, ethyl glycidyl ether,2-ethylhexyl glycidyl ether, allyl glycidyl ether, and alkyleneoxide-functional alkyloxysilanes, for example3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane,3-glycidyloxypropyltripropoxysilane,3-glycidyloxypropylmethyldimethoxysilane,3-glycidyloxypropylethyldiethoxysilane and3-glycidyloxypropyltriisopropoxysilane. The alkylene oxide used ispreferably at least one alkylene oxide selected from the groupconsisting of ethylene oxide and propylene oxide.

Further monomers copolymerizable with alkylene oxides by the process ofthe invention under DMC catalysis are all oxygen-containing cycliccompounds, especially lactones, lactides, aliphatic and aromatic cycliccarboxylic anhydrides and cyclic carbonates. The use thereof isdescribed in U.S. Pat. No. 3,538,043, U.S. Pat. No. 4,500,704, U.S. Pat.No. 5,032,671, U.S. Pat. No. 6,646,100, EP-A-0 222 453 andWO-A-2008/013731.

A number of variants for performance of the process of the invention aredescribed in detail hereinafter. The illustration is merely by way ofexample and should not be understood such that it restricts the presentinvention.

In a preferred embodiment of the invention (variant A), at least onealcohol containing at least two urethane groups, preferably an alcoholof the formula (II), and the double metal cyanide catalyst are firstinitially charged and then the alkylene oxide is added.

Variant A) (“Semi-Batchwise Procedure”):

In variant A) of the process of the invention, at least one alcoholcontaining at least two urethane groups, preferably an alcohol of theformula (II), is first initially charged together with the DMC catalystin a reactor/reactor system. It is optionally possible to add smallamounts of an inorganic mineral acid, preferably phosphoric acid, to thealcohol containing at least two urethane groups prior to contacting withthe DMC catalyst, as described in applications WO-A-99/14258 and EP-A-1577 334, in order to neutralize any traces of base in the alcoholcontaining at least two urethane groups, preferably an alcohol of theformula (II), or in order to generally stabilize the production process.After heating to temperatures of 50° C. to 160° C., preferably 60° C. to140° C., most preferably 70° C. to 140° C., in a preferred processvariant, the reactor contents are stripped with inert gas while stirringover a period of preferably 10 to 60 min. In the course of strippingwith inert gas, volatile constituents, for example traces of water, areremoved with introduction of inert gases into the liquid phase withsimultaneous application of reduced pressure, at an absolute pressure of5 mbar to 500 mbar. After metered addition of typically 5% by weight to20% by weight of one or more alkylene oxides, based on the amount ofalcohol containing at least two urethane groups, preferably an alcoholof the formula (II), initially charged, the DMC catalyst is activated.The addition of one or more alkylene oxides may precede, coincide withor follow the heating of the reactor contents to temperatures of 50° C.to 160° C., preferably 60° C. to 140° C., most preferably 70° C. to 140°C.; it preferably follows after the stripping. The activation of thecatalyst is noticeable by an accelerated drop in the reactor pressure,which indicates the commencement of alkylene oxide conversion. Thedesired amount of alkylene oxide or alkylene oxide mixture can then besupplied continuously to the reaction mixture, and a reactiontemperature of 20° C. to 200° C., preferably of 50° C. to 160° C., morepreferably 70° C. to 150° C., most preferably 80° C. to 140° C., ischosen. The reaction temperature is in many cases identical to theactivation temperature; alternatively, it can be altered on completionof catalyst activation, for example in order not to subject sensitivestarter compounds to excessive thermal stress. It is often the case thatcatalyst activation is effected so quickly that the metered addition ofa separate amount of alkylene oxide for catalyst activation can bedispensed with and it is possible to commence directly, optionally atfirst with a reduced metering rate, with the continuous metered additionof one or more alkylene oxides. The reaction temperature may also bevaried within the limits described over the entire alkylene oxidemetering phase. The alkylene oxides can likewise be supplied to thereactor in different ways: one option is metered addition into the gasphase or directly into the liquid phase, for example by means of animmersed tube or a distributor ring close to the reactor base in a zonewith good mixing. In the case of DMC-catalyzed processes, meteredaddition in the liquid phase is frequently the preferred variant. Theone or more alkylene oxide(s) should be fed continuously to the reactorin such a way that the safety-related pressure limits of the reactorsystem used are not exceeded. Especially in the case of meteredco-addition of ethylene oxide-containing alkylene oxide mixtures or pureethylene oxide, it should be ensured that a sufficient partial inert gaspressure is maintained within the reactor during the startup andmetering phase. This can be established, for example, by means of noblegases or nitrogen. In the case of metered addition into the liquidphase, the metering units should be designed such that they self-empty,for example through provision of metering holes on the underside of thedistributor ring. Generally, apparatus measures, for example theinstallation of non-return valves, should prevent backflow of reactionmedium into the metering units and reactant reservoirs. If an alkyleneoxide mixture is being metered in, the respective alkylene oxides can besupplied to the reactor separately or as a mixture. Premixing of thealkylene oxides with one another can be achieved, for example, by meansof a mixing unit present in the common metering zone (“inlineblending”). It has also been found to be useful to meter the alkyleneoxides, on the pump pressure side, individually or in premixed form intoa pumped circulation system conducted, for example, through one or moreheat exchangers. In that case, for good mixing with the reaction medium,it is advantageous to integrate a high-shear mixing unit into thealkylene oxide/reaction medium stream. The temperature of the exothermicring-opening addition reaction is kept at the desired level by cooling.According to the prior art relating to design of polymerization reactorsfor exothermic reactions (for example Ullmann's Encyclopedia ofIndustrial Chemistry, vol. B4, pp. 167 ff., 5th ed., 1992), such coolingis generally effected via the reactor wall (e.g. jacket, half-coil pipe)and by means of further heat exchange surfaces disposed internally inthe reactor and/or externally in the pumped circulation system, forexample in cooling coils, cooling cartridges, or plate, shell-and-tubeor mixer heat exchangers. This cooling should be designed such thateffective cooling is possible even on commencement of the meteringphase, i.e. with a low fill level.

Generally, good mixing of the reactor contents should be ensured in allreaction phases through design and use of standard stirring units,suitable stirring units here being especially stirrers arranged over oneor more levels or stirrer types which act over the full fill height, forexample gate stirrers (see, for example, Handbuch Apparate [ApparatusHandbook]; Vulkan-Verlag Essen, 1st ed. (1990), p. 188-208). Ofparticular technical relevance here is a specific mixing power which isintroduced on average over the entire reactor contents and is generallyin the range from 0.2 W/L to 5 W/L, based on the reactor volume, withcorrespondingly higher local power inputs in the region of the stirrerunits themselves and possibly in the case of relatively low fill levels.In order to achieve optimal stirring action, combinations of baffles(for example flat or tubular baffles) and cooling coils (or coolingcartridges) may be arranged within the reactor according to the generalprior art, and these may also extend over the vessel base. The stirringpower of the mixing unit may also be varied as a function of the filllevel during the metering phase, in order to ensure a particularly highenergy input in critical reaction phases. Preference is given to usingstirrer units with stirrer levels close to the base. In addition, thestirrer geometry should contribute to reducing the foaming of reactionproducts. The foaming of reaction mixtures can be observed, for example,after the end of the metering and post-reaction phase, when residualalkylene oxides are additionally removed under reduced pressure, atabsolute pressures in the range from 1 mbar to 500 mbar. For such cases,suitable stirrer units have been found to be those which achievecontinuous mixing of the liquid surface. According to the requirement,the stirrer shaft has a base bearing and optionally further supportbearings in the vessel. The stirrer shaft can be driven from the top orbottom (with central or eccentric arrangement of the shaft).

Alternatively, it is also possible to achieve the necessary mixingexclusively by means of a pumped circulation system conducted through aheat exchanger, or to operate this pumped circulation system as afurther mixing component in addition to the stirrer unit, in which casethe reactor contents are pumped in circulation as required (typically 1to 50 times per hour). The specific mixing energy introduced by means ofpumped circulation, for example by means of an external heat exchangeror, in the case of recycling into the reactor, by means of a nozzle orinjector, likewise amounts to values averaging from 0.2 to 5 W/L, thisbeing based on the liquid volume present in the reactor and the pumpedcirculation system at the end of the reaction phase.

A wide variety of different reactor types is suitable for theperformance of the process of the invention. Preference is given tousing cylindrical vessels having a height/diameter ratio of 1.0:1 to10:1. Useful reactor bases include hemispherical, dished, flat orconical bases.

The end of the metered addition of the one or more alkylene oxides maybe followed by a postreaction phase in which residual alkylene oxide isdepleted. The end of this postreaction phase has been attained when nofurther pressure drop can be detected in the reaction tank. Traces ofunreacted alkylene oxides, after the reaction phase, can optionally beremoved quantitatively under reduced pressure, at an absolute pressureof 1 mbar to 500 mbar, or by stripping. Stripping removes volatileconstituents, for example (residual) alkylene oxides, with introductionof inert gases or steam into the liquid phase with simultaneousapplication of reduced pressure, for example by passing inert gasthrough at an absolute pressure of 5 mbar to 500 mbar. The removal ofvolatile constituents, for example of unconverted alkylene oxides,either under reduced pressure or by stirring, is effected attemperatures of 20° C. to 200° C., preferably at 50° C. to 160° C., andpreferably with stirring. Such stripping operations can also beperformed in what are called stripping columns, in which an inert gas orsteam stream is passed counter to the product stream. Preference isgiven to performing the stripping operation with inert gases in theabsence of steam.

After constant pressure has been attained or after volatile constituentshave been removed by reduced pressure and/or stripping, the productobtained by the process of the invention can be discharged from thereactor.

A characteristic of DMC catalysts is their marked sensitivity to highconcentrations of hydroxyl groups which are caused in standardindustrial scale processes for polyether polyol production, for example,by high proportions of starters such as ethylene glycol, propyleneglycol, glycerol, trimethylolpropane, sorbitol or sucrose that arepresent in the reaction mixture at the start of the reaction, and polarimpurities in the reaction mixture or the starter(s). In that case, theDMC catalysts cannot be converted to the polymerization-active formduring the reaction initiation phase. Impurities may, for example, bewater, compounds having a high number of hydroxyl groups closelyadjacent to one another, such as carbohydrates and carbohydratederivatives, or compounds having basic groups, for example amines. Forthe process of the invention, it is of particular significance that evensubstances having urethane groups adjacent to hydroxyl groups do nothave an adverse effect on the catalyst activity. In order neverthelessto be able to subject starters having a high concentration of OH groups,or starters having impurities considered to be catalyst poisons, orstarters having arrangements of functional groups that have adisadvantageous effect on catalyst activity, to DMC-catalyzed alkyleneoxide addition reactions, the hydroxyl group concentration has to belowered, the starter concentration has to be reduced, and the catalystpoisons have to be rendered harmless. For this purpose, for example, itis possible first to use these starter compounds to prepare, by means ofbasic catalysis, prepolymers which, after workup, are then converted bymeans of DMC catalysis to the desired alkylene oxide addition productsof high molar mass. A disadvantage of this procedure is that suchprepolymers often obtained by means of basic catalysis have to be workedup very carefully, in order to rule out deactivation of the DMC catalystby traces of basic catalyst entrained by the prepolymers.

These disadvantages can be overcome by the method of continuous meteredaddition of starter, which is disclosed in WO-A-97/29146. In this case,critical compounds are not initially charged in the reactor but suppliedcontinuously to the reactor during the reaction in addition to thealkylene oxides. Starting media, or what are called H-functional starterpolyols S—I, for the reaction which may be initially charged in thisprocess are alkylene oxide addition products of H-functional startercompounds, for example including those without urethane groups. It isalso possible to use the polyether polyol prepared by the process of theinvention itself, which has been prepared separately beforehand, as thestarting medium (S—I). There is thus no need to first separately prepareprepolymers suitable for further alkylene oxide additions.

Variant B) (“CAOS Semi-Batchwise Procedure”):

In variant B) of the process of the invention, an H-functional starterpolyol S—I and the DMC catalyst are initially charged in the reactorsystem, and at least one alcohol containing at least two urethanegroups, preferably an alcohol of the formula (II), is fed incontinuously together with one or more alkylene oxides. SuitableH-functional starter polyols S—I for this variant are alkylene oxideaddition products, for example polyether polyols, polycarbonate polyols,polyestercarbonate polyols or polyethercarbonate polyols, each, forexample, with OH numbers in the range from 3.0 mg KOH/g to 1000 mgKOH/g, preferably from 3.0 mg KOH/g to 300 mg KOH/g, and/or a polyetherpolyol prepared separately by the process of the invention. Preferenceis given to using a polyether polyol prepared separately by the processof the invention as H-functional starter polyol S—I.

The metered addition of the at least one alcohol containing at least twourethane groups, preferably an alcohol of the formula (II), and the oneor more alkylene oxide(s) is preferably ended simultaneously, or thealcohol containing at least two urethane groups, preferably an alcoholof the formula (II), and a first portion of one or more alkyleneoxide(s) are first metered in together and then the second portion ofone or more alkylene oxides is metered in, the sum total of the firstand second portions of one or more alkylene oxides corresponding to thetotal amount of the one or more alkylene oxides used. The first portionis preferably 60% by weight to 98% by weight and the second portion is40% by weight to 2% by weight of the total amount of one or morealkylene oxides to be metered in. If the composition of the alkyleneoxide metering stream is altered after the end of the metered additionof the alcohol containing at least two urethane groups, preferably analcohol of the formula (II), it is also possible to prepare productshaving multiblock structures by process variant B). The metered additionof the reagents may be followed by a postreaction phase in which theconsumption of alkylene oxide can be quantified by monitoring thepressure. On attainment of constant pressure, optionally afterapplication of reduced pressure or by stripping to remove unconvertedalkylene oxides, as described above, the product can be discharged.

It is alternatively also possible, in variant B of the process of theinvention, in addition to the alcohol containing at least two urethanegroups, preferably an alcohol of the formula (II), also to use theabove-described H-functional starter compounds which are not alcoholscontaining at least two urethane groups in a continuous manner togetherwith one or more alkylene oxides.

Variant C (“Continuous CAOS Procedure”):

In a further preferred embodiment of the process of the invention(variant C), an H-functional starter polyol S—I and a portion of thedouble metal cyanide catalyst are initially charged, and then at leastone alcohol containing at least two urethane groups, preferably analcohol of the formula (II), and further double metal cyanide catalystare fed in continuously together with the alkylene oxide, withcontinuous withdrawal of the polyether polyol formed here from thereaction system after a preselectable mean residence time.

In variant C) of the process of the invention, the polyether polyols areprepared in a fully continuous manner. A fully continuous process forpreparing alkylene oxide addition products is described in principle inWO-A-98/03571. The procedure disclosed therein is applicable to theperformance of the process of the invention. In this variant, as well asone or more alkylene oxides and at least one alcohol containing at leasttwo urethane groups, preferably an alcohol of the formula (II), the DMCcatalyst is also fed continuously to the reactor or a reactor systemunder alkoxylation conditions, and the polyether polyol is withdrawncontinuously from the reactor or the reactor system after apreselectable mean residence time. For startup of such a fullycontinuous process, a starter polyol S—I and a portion of the DMCcatalyst are initially charged. Suitable starter polyols S—I for variantC) of the process of the invention are alkylene oxide addition products,for example polyether polyols, polycarbonate polyols, polyestercarbonatepolyols, polyethercarbonate polyols, for example, with OH numbers in therange from 3.0 mg KOH/g to 1000 mg KOH/g, preferably from 3.0 mg KOH/gto 300 mg KOH/g, and/or a polyether polyol prepared by the process ofthe invention, which has been prepared separately beforehand. Preferenceis given to using polyether polyol prepared by the process of theinvention which has previously been prepared separately as starterpolyol in variant C of the process of the invention.

For example, the reactor is operated in such a way that it has beenfilled completely with the reaction mixture (“liquid-full” mode).

Continuous postreaction steps may follow, for example in a reactorcascade or a tubular reactor. The volatile constituents can be removedunder reduced pressure and/or by stripping, as described above.

For example, in a subsequent step, the reaction mixture removedcontinuously, which generally has an alkylene oxide content of from0.05% by weight to 10% by weight, may be transferred into a postreactorin which, by way of a postreaction, the content of free alkylene oxideis reduced to less than 0.05% by weight in the reaction mixture. Thepostreactor may be a tubular reactor, a loop reactor or a stirred tankfor example. The pressure in this postreactor is preferably at the samepressure as in the reaction apparatus in which the preceding reactionstep of the addition of the alkylene oxides onto alcohols containing atleast two urethane groups, preferably alcohols of the formula (II), isperformed. The temperature in the downstream reactor is preferably 50°C. to 150° C. and more preferably 80° C. to 140° C.

In particularly preferred embodiments of variants B and C of the processof the invention, the starter polyol S—I used is a polyether polyol ofthe invention or a polyether polyol obtainable by the process of theinvention.

The present invention further provides a polyether polyol obtainable bythe process of the invention.

The OH numbers of the polyether polyols obtained preferably have valuesof 3 mg KOH/g to 400 mg KOH/g, more preferably of 10 mg KOH/g to 200 mgKOH/g, most preferably of 20 mg KOH/g to 150 mg KOH/g. This is trueirrespective of the process variant used (A, B or C).

The equivalent molar mass is understood to mean the total mass of thematerial containing active hydrogen atoms divided by the number ofactive hydrogen atoms.

In the case of materials containing hydroxyl groups, it is in thefollowing relationship with the OH number:

equivalent molar mass=56 100/OH number [mg KOH/g]

It is optionally possible to add ageing stabilizers, for exampleantioxidants, to the polyether polyols obtainable by the processaccording to the invention.

The present invention further relates to the use of a polyether polyolof the invention for preparation of a polyurethane polymer, preferably aflexible polyurethane foam, more preferably a flexible slabstockpolyurethane foam or a flexible molded polyurethane foam.

The present invention further provides a polyurethane polymer,preferably a flexible polyurethane foam, more preferably a flexibleslabstock polyurethane foam or a flexible molded polyurethane foam,obtainable by reacting a polyisocyanate with a polyether polyol of theinvention by a method familiar to the person skilled in the art, withthe aid of standard additives, for example activators, stabilizers,blowing agents, crosslinkers, chain extenders and/or fillers, andoptionally further polyether polyols, polyester polyols,polyethercarbonate polyols, polycarbonate polyols and/orfiller-containing polyols (polymer polyols, polyurea dispersions, etc.).

Suitable polyisocyanates are aliphatic, cycloaliphatic, araliphatic,aromatic and heterocyclic polyisocyanates, as described, for example, byW. Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136,for example those of the formula (XI)

Q(NCO)_(n),  (XI)

in which

-   n=2-4, preferably 2-3,-   and-   Q is an aliphatic hydrocarbyl radical having 2-18 and preferably    6-10 carbon atoms, a cycloaliphatic hydrocarbyl radical having 4-15    and preferably 6-13 carbon atoms or an araliphatic hydrocarbyl    radical having 8-15 and preferably 8-13 carbon atoms.

For example, the polyisocyanates are those as described in EP 0 007 502A1, pages 7-8. Preference is generally given to the readily industriallyavailable polyisocyanates, for example tolylene 2,4- and2,6-diisocyanate and any desired mixtures of these isomers (“TDI”);polyphenylpolymethylene polyisocyanates as prepared byaniline-formaldehyde condensation and subsequent phosgenation (“crudeMDI”), and polyisocyanates having carbodiimide groups, urethane groups,allophanate groups, isocyanurate groups, urea groups or biuret groups(“modified polyisocyanates”), especially those modified polyisocyanateswhich derive from tolylene 2,4- and/or 2,6-diisocyanate or fromdiphenylmethane 4,4′- and/or 2,4′-diisocyanate. The polyisocyanatescontaining urethane groups (prepolymers) may, for example, be reactionproducts of the polyisocyanates with polyester polyols or else any otherpolyols (for example conventional polyether polyols). The polyisocyanateused is preferably at least one compound selected from the groupconsisting of tolylene 2,4- and 2,6-diisocyanate, diphenylmethane 4,4′-and 2,4′- and 2,2′-diisocyanate and polyphenylpolymethylenepolyisocyanate (“multiring MDI”); the polyisocyanate used is morepreferably a mixture comprising diphenylmethane 4,4′-diisocyanate anddiphenylmethane 2,4′-diisocyanate and polyphenylpolymethylenepolyisocyanate.

As well as the aforementioned polyisocyanates, it is additionally alsopossible to use conventional polyether polyols for the preparation ofthe polyurethane polymers. Conventional polyether polyols in the contextof the invention are understood to mean the alkylene oxide additionproducts of starter compounds having Zerewitinoff-active hydrogen atoms.Examples of such polyether polyols are known to those skilled in theart. They may have a hydroxyl number to DIN 53240 of ≥3.0 mg KOH/g to≤1000 mg KOH/g, preferably of ≥5.0 mg KOH/g to ≤600 mg KOH/g. Thestarter compounds having Zerewitinoff-active hydrogen atoms used for thepreparation of the conventional polyether polyols usually havefunctionalities of 2 to 8. The starter compounds may behydroxy-functional and/or amino-functional. Examples ofhydroxy-functional starter compounds are propylene glycol, ethyleneglycol, diethylene glycol, dipropylene glycol, butane-1,2-diol,butane-1,3-diol, butane-1,4-diol, hexanediol, pentanediol,3-methylpentane-1,5-diol, dodecane-1,12-diol, glycerol,trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, sucrose,hydroquinone, catechol, resorcinol, bisphenol F, bisphenol A,1,3,5-trihydroxybenzene, methylol-containing condensates of formaldehydeand phenol or melamine or urea. Examples of amino-functional startercompounds are ammonia, ethanolamine, diethanolamine, triethanolamine,isopropanolamine, diisopropanolamine, ethylenediamine,hexamethylenediamine, aniline, the isomers of toluidine, the isomers ofdiaminotoluene, the isomers of diaminodiphenylmethane, and higherpolycyclic products obtained in the condensation of aniline withformaldehyde to give diaminodiphenylmethane.

Suitable alkylene oxides for the conventional polyether polyols are, forexample, ethylene oxide, propylene oxide, 1,2-butylene oxide or2,3-butylene oxide and styrene oxide. Preference is given to feedingpropylene oxide and ethylene oxide into the reaction mixtureindividually, in a mixture or successively. If the alkylene oxides aremetered in successively, the products produced contain polyether chainshaving block structures. Products having ethylene oxide end blocks arecharacterized, for example, by elevated concentrations of primary endgroups which impart advantageous isocyanate reactivity to the systems.

The preparation of the conventional polyether polyols may bebase-catalyzed, for example via alkali metal hydroxide or aminecatalysis, double metal cyanide-catalyzed, or acid-catalyzed by Lewis orBrønsted acids.

As well as the aforementioned conventional polyether polyols, it isadditionally or alternatively also possible to use polyester polyols forthe preparation of the polyurethane polymers. Suitable polyester polyolspreferably have OH numbers in the range from 6 to 800 mg KOH/g and canbe prepared, for example, from polyfunctional carboxylic acids,preferably organic dicarboxylic acids having 2 to 12 carbon atoms, andpolyhydric alcohols, preferably diols, having 2 to 12 carbon atoms,preferably 2 to 6 carbon atoms, by known methods. Rather than thepolyfunctional carboxylic acids, it is also possible to use derivativesthereof, for example acid chlorides or anhydrides.

In a first embodiment, the invention thus relates to a process forpreparing polyether polyols by addition of alkylene oxides ontoH-functional starter compounds, characterized in that at least onealcohol containing at least two urethane groups is used as H-functionalstarter compound.

In a second embodiment, the invention relates to a process according tothe first embodiment, characterized in that at least one alcoholcontaining two urethane groups is used as H-functional starter compound.

In a third embodiment, the invention relates to a process according tothe second embodiment, characterized in that at least one alcoholcontaining two urethane groups of formula (II) is used as H-functionalstarter compound

where

-   R¹ is linear or branched C₂ to C₂₄-alkylene which may optionally be    interrupted by heteroatoms such as O, S or N and may be substituted,    preferably CH₂—CH₂ or CH₂—CH(CH₃),-   R² is linear or branched C₂ to C₂₄-alkylene, C₃ to    C₂₄-cycloalkylene, C₄ to C₂₄-arylene, C₅ to C₂₄-aralkylene, C₂ to    C₂₄-alkenylene, C₂ to C₂₄-alkynylene, each of which may optionally    be interrupted by heteroatoms such as O, S or N and/or each of which    may be substituted by alkyl, aryl and/or hydroxyl, preferably C₂ to    C₂₄-alkylene,-   R³ is H, linear or branched C₁ to C₂₄-alkyl, C₃ to C₂₄-cycloalkyl,    C₄ to C₂₄-aryl, C₅ to C₂₄-aralkyl, C₂ to C₂₄-alkenyl, C₂ to    C₂₄-alkynyl, each of which may optionally be interrupted by    heteroatoms such as O, S or N and/or each of which may be    substituted by alkyl, aryl and/or hydroxyl, preferably H,-   R⁴ is H, linear or branched C₁ to C₂₄-alkyl, C₃ to C₂₄-cycloalkyl,    C₄ to C₂₄-aryl, C₅ to C₂₄-aralkyl, C₂ to C₂₄-alkenyl, C₂ to    C₂₄-alkynyl, each of which may optionally be interrupted by    heteroatoms such as O, S or N and/or each of which may be    substituted by alkyl, aryl and/or hydroxyl, preferably H,-   R⁵ is linear or branched C₂ to C₂₄-alkylene which may optionally be    interrupted by heteroatoms such as O, S or N and may be substituted,    preferably CH₂—CH₂ or CH₂—CH(CH₃),    and where R¹ to R⁵ may be identical or different.

In a fourth embodiment, the invention relates to a process according tothe third embodiment, where

-   -   R¹═CH₂—CH₂ or CH₂—CH(CH₃),    -   R²═C₂ to C₂₄-alkylene,    -   R³═R⁴═H, and    -   R⁵═CH₂—CH₂ or CH₂—CH(CH₃).

In a fifth embodiment, the invention relates to a process according toany of embodiments 1 to 4, characterized in that the alcohol containingat least two urethane groups is obtainable by reacting cyclic carbonateswith compounds having at least two amino groups.

In a sixth embodiment, the invention relates to a process according toany of embodiments 1 to 5, characterized in that the alcohol containingat least two urethane groups is obtainable by reacting propylenecarbonate and/or ethylene carbonate with compounds having at least twoamino groups.

In a seventh embodiment, the invention relates to a process according toany of embodiments 1 to 6, characterized in that the alcohol containingtwo urethane groups is obtainable by reacting propylene carbonate and/orethylene carbonate with diamines of formula (III)

HN(R³)—R²—NH(R⁴)  (III)

where R² to R⁴ may be identical or different and may be as defined inembodiments 3 and 4.

In an eighth embodiment, the invention relates to a process according toany of embodiments 1 to 7, characterized in that the alcohol containingtwo urethane groups is obtainable by reacting propylene carbonate and/orethylene carbonate with at least one compound selected from the groupconsisting of 1,2-ethanediamine, diaminopropane, diaminopentane,diaminohexane, diaminooctane, diaminodecane, diaminododecane,diaminooctadecane, diaminoeicosane, isophoronediamine, tolylenediamine,and methylenedianiline.

In a ninth embodiment, the invention relates to a process according toany of embodiments 1 to 8, characterized in that the alkylene oxide usedis at least one alkylene oxide selected from the group consisting ofethylene oxide and propylene oxide.

In a tenth embodiment, the invention relates to a process according toany of embodiments 1 to 9, wherein the addition is effected in thepresence of at least one DMC catalyst.

In an eleventh embodiment, the invention relates to a process accordingto embodiment 10, wherein at least one alcohol containing at least twourethane groups and the double metal cyanide catalyst are firstinitially charged and then the alkylene oxide is added.

In a twelfth embodiment, the invention relates to a process according toany of embodiments 1 to 11, wherein alcohol containing at least twourethane groups is metered continuously into the reactor as H-functionalstarter compound during the reaction, and wherein the resulting reactionmixture is removed continuously from the reactor after a preselectablemean residence time.

In a thirteenth embodiment, the invention relates to a process accordingto embodiment 10, wherein an H-functional starter polyol S—I and thedouble metal cyanide catalyst are initially charged in a reactor andthen at least one alcohol containing at least two urethane groups ismetered continuously into this reactor together with one or morealkylene oxides, wherein the H-functional starter polyol S—I has an OHnumber in the range from 3 mg KOH/g to 1000 mg KOH/g, and wherein theresulting reaction mixture is removed continuously from the reactorafter a preselectable mean residence time.

In a fourteenth embodiment, the invention relates to a process accordingto embodiment 12 or 13, wherein DMC catalyst is additionally alsometered continuously into the reactor.

In a fifteenth embodiment, the invention relates to a process accordingto any of embodiments 12 to 14, wherein the reaction mixture removedcontinuously from the reactor with a content of 0.05% by weight to 10%by weight of alkylene oxide is transferred into a postreactor in which,by way of a postreaction, the content of free alkylene oxide is reducedto less than 0.05% by weight in the reaction mixture.

In a sixteenth embodiment, the invention relates to a process accordingto embodiment 13, characterized in that the starter polyol S—I used is apolyether polyol containing a structural unit of the formula (IV)

where R¹ to R⁵ may be identical or different and are as defined inclaims 3 and 4, ora polyether polyol obtainable by a process according to any ofembodiments 1 to 15.

In a seventeenth embodiment, the invention relates to polyether polyolscontaining a structural unit of the formula (IV)

where R¹ to R⁵ may be identical or different and are as defined inembodiments 3 and 4.

In an eighteenth embodiment, the invention relates to polyether polyolsaccording to embodiment 17, characterized in that these have an OHnumber in the range from 3 to 400 mg KOH/g, preferably from 10 to 200 mgKOH/g.

In a nineteenth embodiment, the invention relates to polyether polyolsobtainable by a process according to any of embodiments 1 to 16.

In a twentieth embodiment, the invention relates to the use of apolyether polyol according to any of embodiments 17 to 19 forpreparation of a polyurethane polymer, preferably a flexiblepolyurethane foam.

In a twenty-first embodiment, the invention relates to a polyurethanepolymer, preferably a flexible polyurethane foam, obtainable by reactinga polyisocyanate with a polyether polyol according to any of embodiments17 to 19.

EXAMPLES

Test Methods:

Experimentally determined OH numbers were determined by the method ofDIN 53240.

The amine numbers (NH number) were determined by the method of DIN53176.

The viscosities were determined by means of a rotary viscometer (PhysicaMCR 51, manufacturer: Anton Paar) by the method of DIN 53018.

The determination of the functionality of the starter in the finishedpolyether polyol was conducted by means of ¹³C NMR (from Bruker, Advance400, 400 MHz; wait time d1: 4 s, 6000 scans). Each sample was dissolvedin deuterated acetone-D6 with addition of chromium(III) acetylacetonate.The solution concentration was 500 mg/mL.

The relevant resonances in the ¹³C NMR (based on CHCl₃=7.24 ppm) are asfollows:

The carbon signals of the carbon atoms bonded directly to the nitrogen(methylene groups, methine group) of the starter are evaluated:

Bifunctionally started: 40.4 ppm to 40.0 ppm (one carbon)

Tri- and tetrafunctionally started: 42.2 ppm to 40.5 ppm (two carbons)

Bifunctionally started means that only the OH groups of the diurethanediol starter compound are alkoxylated.

Tri- and tetrafunctionally started means that the OH groups and one orboth of the NH groups of the urethane bond of the diurethane diolstarter compound are alkoxylated.

The chemical shifts in the ¹³C NMR were determined by comparativemeasurements (comparative spectra).

The apparent densities and the compression hardnesses (40% compression,4^(th) cycle) were determined to DIN EN ISO 3386-1.

Raw Materials Used:

Catalyst for the Alkylene Oxide Addition (DMC Catalyst):

Double metal cyanide catalyst, containing zinc hexacyanocobaltate,tert-butanol and polypropylene glycol having a number-average molecularweight of 1000 g/mol, according to example 6 in WO-A 01/80994.

Cyclic propylene carbonate (cPC): from Acros.

Cyclic ethylene carbonate (cEC): from Acros.

1,3-Diaminopropane, Sigma-Aldrich

1,5-Diaminopentane, Sigma-Aldrich

Stabilizer 1: siloxane-based foam stabilizer, Tegostab® BF 2370, EvonikGoldschmidt

Isocyanate 1: mixture of 80% by weight of tolylene 2,4- and 20% byweight of tolylene 2,6-diisocyanate, available under the Desmodur® T 80name, Bayer MaterialScience AG

Catalyst 1: bis(2-dimethylaminoethyl) ether in dipropylene glycol,available as Addocat® 108, from Rheinchemie

Catalyst 2: tin(II) ethylhexanoate, available as Dabco® T-9, from AirProducts

Preparation of Diurethane Diols:

The alcohols of the invention prepared in examples 1 and 2 contain twohydroxyl groups and two urethane groups, and are therefore referred toas diurethane diols.

Example 1

A 2 L four-neck flask having a reflux condenser and thermometer wasinitially charged with cyclic propylene carbonate (919 g, 9 mol).Subsequently, 1,3-diaminopropane (222 g, 3 mol) was gradually addeddropwise at 60° C. The reaction was subsequently stirred at 60° C. for afurther 24 h in total. After cooling to 25° C., the diurethane diol wasobtained.

Product properties of the resulting diurethane diol:

OH number: 295 mg KOH/g

NH number: 0.8 mg KOH/g

Viscosity (25° C.): 2000 mPas

Example 2

A 2 L four-neck flask with reflux condenser and thermometer wasinitially charged with cyclic propylene carbonate (766 g, 7.5 mol).Subsequently, 1,5-diaminopentane (255 g, 2.5 mol) was gradually addeddropwise. The reaction was subsequently stirred at 60° C. for a further24 h in total. After cooling to 25° C., the diurethane diol wasobtained.

Product properties of the resulting diurethane diol:

OH number: 278 mg KOH/g

NH number: 0.9 mg KOH/g

Viscosity (25° C.): 2100 mPas

Preparation of Polyether Polyols Example 3 (Semi-Batchwise CAOS Method)

A 2 liter stainless steel pressure reactor was initially charged with200 g of a trifunctional poly(oxypropylene-oxyethylene) polyol having anethylene oxide content of 10.5% (Arcol® polyol 1108) and OH number=48 mgKOH/g and 234 mg of DMC catalyst under nitrogen, and heated to 130° C.Stripping was accomplished by introducing nitrogen into the reactionmixture at 130° C. for a period of 30 min and simultaneously applying areduced pressure (in absolute terms), such that a reduced pressure of0.1 bar (absolute) was established in the reactor. Then, at 130° C.while stirring (800 rpm), 20 g of propylene oxide were first meteredinto the reactor within 5 min. Subsequently, over a period of 6 h, 781 gof propylene oxide and 179 g of diurethane diol from example 1 weremetered into the reactor at 130° C. while stirring (800 rpm). Finally,at 130° C. while stirring (800 rpm), a further 20 g of propylene oxidewere metered into the reactor within 10 min. After a postreaction timeof 90 min at 130° C., volatile constituents were distilled off underreduced pressure at 50 mbar (absolute) and 130° C. for 60 minutes andthen the reaction mixture was cooled to room temperature.

Product Properties:

OH number: 49.3 mg KOH/g

Viscosity (25° C.): 1348 mPas

Example 4 (Semi-Batchwise CAOS Method)

A 2 liter stainless steel pressure reactor was initially charged with200 g of the polyether polyol from example 3 and 200 mg of DMC catalystunder nitrogen, and heated to 130° C. Stripping was accomplished byintroducing nitrogen into the reaction mixture at 130° C. for a periodof 30 min and simultaneously applying a reduced pressure (in absoluteterms), such that a reduced pressure of 0.1 bar (absolute) wasestablished in the reactor. Then, at 130° C. while stirring (800 rpm),20 g of propylene oxide were first metered into the reactor within 5min. Subsequently, over a period of 6.5 h, 782 g of propylene oxide and178 g of diurethane diol from example 1 were metered into the reactor at130° C. while stirring (800 rpm). Finally, at 130° C. while stirring(800 rpm), a further 20 g of propylene oxide were metered into thereactor within 10 min. After a postreaction time of 45 min at 130° C.,volatile constituents were distilled off under reduced pressure at 50mbar (absolute) and 130° C. for 60 minutes and then the reaction mixturewas cooled to room temperature.

Product Properties:

OH number: 47.5 mg KOH/g

Viscosity (25° C.): 1410 mPas

Example 5 (Semi-Batchwise CAOS Method)

A 2 liter stainless steel pressure reactor was initially charged with200 g of the polyether polyol from example 4 and 200 mg of DMC catalystunder nitrogen, and heated to 130° C. Stripping was accomplished byintroducing nitrogen into the reaction mixture at 130° C. for a periodof 30 min and simultaneously applying a reduced pressure (in absoluteterms), such that a reduced pressure of 0.1 bar (absolute) wasestablished in the reactor. Then, at 130° C. while stirring (800 rpm),20 g of propylene oxide were first metered into the reactor within 5min. Subsequently, over a period of 7 h, 770 g of propylene oxide and190 g of diurethane diol from example 2 were metered into the reactor at130° C. while stirring (800 rpm). Finally, at 130° C. while stirring(800 rpm), a further 20 g of propylene oxide were metered into thereactor within 10 min. After a postreaction time of 60 min at 130° C.,volatile constituents were distilled off under reduced pressure at 50mbar (absolute) and 130° C. for 60 minutes and then the reaction mixturewas cooled to room temperature.

Product Properties:

OH number: 44.8 mg KOH/g

Viscosity (25° C.): 1495 mPas

Example 6 (Semi-Batchwise CAOS Method)

A 2 liter stainless steel pressure reactor was initially charged with195 g of the polyether polyol from example 5 and 20 mg of DMC catalystunder nitrogen, and heated to 130° C. Stripping was accomplished byintroducing nitrogen into the reaction mixture at 130° C. for a periodof 30 min and simultaneously applying a reduced pressure (in absoluteterms), such that a reduced pressure of 0.1 bar (absolute) wasestablished in the reactor. Then, at 130° C. while stirring (800 rpm),20 g of propylene oxide were first metered into the reactor within 5min. Subsequently, over a period of 7 h, 759 g of propylene oxide and206 g of diurethane diol from example 2 were metered into the reactor at130° C. while stirring (800 rpm). Finally, at 130° C. while stirring(800 rpm), a further 20 g of propylene oxide were metered into thereactor within 10 min. After a postreaction time of 90 min at 130° C.,volatile constituents were distilled off under reduced pressure at 50mbar (absolute) and 130° C. for 60 minutes and then the reaction mixturewas cooled to room temperature.

Product Properties:

OH number: 49.1 mg KOH/g

Viscosity (25° C.): 1438 mPas

Functionality: 2.07

Production of Flexible Polyurethane Foams Examples 7 & 8: (withPolyether Polyols from Example 4 and Example 6)

In a mode of processing by the one-stage method which is customary forthe production of polyurethane foams, the in the examples of thefeedstocks listed in table 1 below were reacted with one another.

Polyurethane foams were produced according to the recipes specified inthe table below. The proportions of the components are listed in partsby weight. High-quality flexible foams having homogeneous cell structurewere obtained, which were characterized by determining the apparentdensities and compression hardnesses.

TABLE 1 Preparation of flexible polyurethane foams Example 7a 7b 8a 8bPolyol from example 4 100 100 — — Polyol from example 6 — — 100 100Stabilizer 1 1.2 1.2 1.2 1.2 Catalyst 1 0.15 0.12 0.15 0.12 Catalyst 20.12 0.18 0.12 0.18 Water 2.50 4.50 2.50 4.50 Isocyanate 1 34.1 55.034.4 55.2 NCO index 104 106 104 106 Apparent density (kg/m³) 41.2 28.037.4 25.6 Compression hardness, 4th cycle 4.1 4.1 3.4 4.2 (kPa)

Examples 7a, 7b, 8a and 8b demonstrate that the polyether polyols of theinvention are suitable for the production of polyurethanes (here:flexible polyurethane foams).

1. A process for preparing polyether polyols comprising adding alkyleneoxides onto H-functional starter compounds, wherein the H-functionalstarter compound comprises at least one alcohol containing at least twourethane groups.
 2. The process as claimed in claim 1, wherein theH-functional starter compound comprises at least one alcohol containingtwo urethane groups.
 3. The process as claimed in claim 2, wherein saidalcohol containing two urethane groups corresponds to the formula (II)

wherein: R¹ represents a linear or branched C₂- to C₂₄-alkylene whichmay optionally be interrupted by heteroatoms such as O, S or N and maybe substituted, R² represents a linear or branched C₂- to C₂₄-alkylene,C₃- to C₂₄-cycloalkylene, C₄- to C₂₄-arylene, C₅- to C₂₄-aralkylene, C₂-to C₂₄-alkenylene, C₂- to C₂₄-alkynylene, each of which may optionallybe interrupted by heteroatoms such as O, S or N and/or each of which maybe substituted by alkyl, aryl and/or hydroxyl, R³ represents a H atom,linear or branched C₁- to C₂₄-alkyl, C₃- to C₂₄-cycloalkyl, C₄- toC₂₄-aryl, C₅- to C₂₄-aralkyl, C₂- to C₂₄-alkenyl, C₂- to C₂₄-alkynyl,each of which may optionally be interrupted by heteroatoms such as O, Sor N and/or each of which may be substituted by alkyl, aryl and/orhydroxyl, R⁴ represents a H atom, linear or branched C₁- to C₂₄-alkyl,C₃- to C₂₄-cycloalkyl, C₄- to C₂₄-aryl, C₅- to C₂₄-aralkyl, C₂- toC₂₄-alkenyl, C₂- to C₂₄-alkynyl, each of which may optionally beinterrupted by heteroatoms such as O, S or N and/or each of which may besubstituted by alkyl, aryl and/or hydroxyl, R⁵ represents a linear orbranched C₂- to C₂₄-alkylene which may optionally be interrupted byheteroatoms such as O, S or N and may be substituted; and each of R¹ toR⁵ may be identical or different.
 4. The process as claimed in claim 3,wherein R¹ represents CH₂—CH₂ or CH₂—CH(CH₃), R² represents C₂- toC₂₄-alkylene, R³ and R⁴=each represent a H atom, and R⁵ representsCH₂—CH₂ or CH₂—CH(CH₃).
 5. The process as claimed in claim 1, whereinsaid alcohol containing at least two urethane groups is obtainable byreacting cyclic carbonates with compounds having at least two aminogroups.
 6. The process as claimed in claim 1, wherein said alcoholcontaining at least two urethane groups is obtainable by reactingpropylene carbonate and/or ethylene carbonate with compounds having atleast two amino groups.
 7. The process as claimed in claim 1, whereinsaid alcohol containing at least two urethane groups is obtainable byreacting propylene carbonate and/or ethylene carbonate with diamines offormula (III)HN(R³)—R²—NH(R⁴)  (III) wherein: R² to R⁴ may be identical or differentand R² represents a linear or branched C₂- to C₂₄-alkylene, C₃- toC₂₄-cycloalkylene, C₄- to C₂₄-arylene, C₅- to C₂₄-aralkylene, C₂- toC₂₄-alkenylene, C₂- to C₂₄-alkynylene, each of which may optionally beinterrupted by heteroatoms such as O, S or N and/or each of which may besubstituted by alkyl, aryl and/or hydroxyl, R³ represents a H atom,linear or branched C₁- to C₂₄-alkyl, C₃- to C₂₄-cycloalkyl, C₄- toC₂₄-aryl, C₅- to C₂₄-aralkyl, C₂- to C₂₄-alkenyl, C₂- to C₂₄-alkynyl,each of which may optionally be interrupted by heteroatoms such as O, Sor N and/or each of which may be substituted by alkyl, aryl and/orhydroxyl, and R⁴ represents a H atom, linear or branched C₁- toC₂₄-alkyl, C₃- to C₂₄-cycloalkyl, C₄ to C₂₄-aryl, C₅- to C₂₄-aralkyl,C₂- to C₂₄-alkenyl, C₂- to C₂₄-alkynyl, each of which may optionally beinterrupted by heteroatoms such as O, S or N and/or each of which may besubstituted by alkyl, aryl and/or hydroxyl.
 8. The process as claimed inclaim 1, wherein said alcohol containing at least two urethane groups isobtainable by reacting propylene carbonate and/or ethylene carbonatewith at least one compound which comprises at least one of1,2-ethanediamine, diaminopropane, diaminopentane, diaminohexane,diaminooctane, diaminodecane, diaminododecane, diaminooctadecane,diaminoeicosane, isophoronediamine, tolylenediamine, andmethylenedianiline.
 9. The process as claimed in claim 1, wherein addingalkylene oxides onto H-functional starter compounds occurs in thepresence of at least one DMC catalyst.
 10. The process as claimed inclaim 1, wherein adding of said alcohol containing at least two urethanegroups is effected by metering said alcohol continuously into thereactor as H-functional starter substance during the reaction, andwherein the resulting reaction mixture is removed continuously from thereactor after a preselectable mean residence time.
 11. The process asclaimed in claim 9, comprising initially charging an H-functionalstarter polyol S—I and the double metal cyanide catalyst into a reactor,and then continuously metering at least one alcohol containing at leasttwo urethane groups into this reactor together with one or more alkyleneoxides, wherein the H-functional starter polyol S—I has an OH number inthe range from 3 mg KOH/g to 1000 mg KOH/g, and wherein the resultingreaction mixture is removed continuously from the reactor after apreselectable mean residence time.
 12. The process as claimed in claim10, wherein DMC catalyst is also continuously metered into the reactor.